1. Field of the Invention
The present invention relates to a technology for protecting copyrights of various types of digital contents when the copyrights of such digital contents are executed in a system which is composed of a recording reproducing apparatus such as a hard disk recorder, a data processing system such as a personal computer and so on.
2. Description of the Related Art
Recently, technologies for digitizing information is developed, storage units for storing information therein tend to become large in capacity, and broadband networks are widely deployed. With this tendency, contents containing video data (moving picture data), audio data, image data and so on tend to be formed into digital information and stored in various types of recording media such as storage units, rewritable media and so on.
However, when such technology development makes it easy for a user to effect data conversion from one type into another one, with intention or without intention, the user tends to distribute or transfer the data without license of the copyright holder of the contents, with the result that copyrights will often suffer from risk of infringement.
For this reason, in order to protect copyrights of the contents, technologies for enciphering such copyright materials have been developed so far. When such technologies are introduced into a situation where the copyright materials are handled with a data management system, encryption data (hereinafter referred to as enciphered data) becomes meaningless unless a key for deciphering the ciphertext is obtained. Therefore, it follows that the encryption system is effective for protecting copyrights.
However, when an application software (hereinafter simply referred to as application) is activated to access the enciphered data for utilizing the data, it becomes necessary to decipher the enciphered data and store the same in a recording medium. In this way, when the data is once deciphered to be a plaintext and the resulting plaintext is stored in the recording medium, the user becomes allowed to carry out any operation such as transferring, copying, falsification and so on. Thus, there can be a concern that the copyright protection does not function in this situation.
In order to cope with this situation, there has been proposed a technology which is disclosed in Japanese Patent laid-open gazette No. 2000-311114, No. 2000-330870 or the like.
According to the technology disclosed in the gazettes, when a rewritable medium is utilized, a media ID (Identification) inherent to the medium is utilized as the encryption key. As for a medium having no media ID, an encryption key written in a read-in region, an exchange processing region, a ROM (Read Only Memory) which a file system is ordinarily prohibited to access, is utilized. As for a medium having no particular ROM region such as a hard disk drive or the like, a device ID involved in a BIOS (Basic Input Output System) in a concealing manner is utilized as the encryption key. According to the technology disclosed in the aforesaid gazette, data enciphered with these types of encryption keys is stored in a medium, whereby the copyright protection is made effective.
Meanwhile, if a storage medium containing an enciphered copyright material (contents) is additionally attached to a personal computer, data recording reproducing apparatus or the like which is operated without copyright protection function, a situation can be brought about in which a storage medium with no encryption function (hard disk for storing data of no necessity in undergoing encryption processing) and a storage medium with encryption function (hard disk designed for storing encrypted data) are operated in a mixed fashion.
Under this situation, if an application is activated to read the enciphered data and utilize the same, the data of copyright material released from enciphered status can be wholly or partly read, with the result that the data of copyright material can be transferred from one person to another without regulation. The aforesaid conventional technology does not mention any countermeasure against the situation where the material can suffer from copyright infringement.
For example, an assumption is introduced that when an editing application is activated to change the data, the data in the halfway of processing stage may be temporarily stored in a file or a memory file. In this case, the temporary stored file having contents meaningful as a copyright material is created in a medium other than a medium as an object of encryption. That is, data having not undergone enciphering process is stored in the file or the memory file. At this time, if a system for protecting copyrights is tried to be built by using an existing file system, then a converting work is requested, i.e., all data stored in the hard disk are enciphered. However, if such system were built, even the copyright holder or a person licensed by the copyright holder can be stringently restricted upon executing the copyrights. Therefore, the copyrights cannot be executed in a reasonable manner.